Conrad’s false mussel Mytilopsis leucophaeata (Bivalvia: Dreissenidae) in the Ponto-Caspian region: a synthesis of data

This study summarizes the available data on the distribution of Conrad’s false mussel Mytilopsis leucophaeata, a highly invasive North American bivalve, in the Ponto-Caspian region. It provides new records of this species from the Black, Azov and Caspian Sea and gives a synopsis of known information on its taxonomy, invasion history, and ecology, with special regard to temperature and salinity and adaptive potential for further spread in the region. In all three sea basins, M. leucophaeata seems to slowly continue extending its invasion range. Its occurrence is strongly associated with the areas of major freshwater input. In the Sea of Azov, the recorded salinity for this species is much lower than the maximum salinity for the basin, while in the Black and Caspian seas it colonizes biotopes with a salinity close to the respective maximum. In general, the existing pattern of M. leucophaeata dispersal can only partially be explained by such limiting factors as salinity and temperature. Whatever the nature of these factors, this species has not yet colonized some water areas, that appear suitable for its expansion, first of all, southern and south-western parts of the Black Sea. Based on the COI gene Conrad’s false mussels from all over Europe, including the Ponto-Caspian region, belong to the same haplotype, a cold-tolerant lineage of mid-eastern or northeastern USA origin which can represent a separate (sub)species.